<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        /**
         * Document节点的子节点可以是DocumentType、Element()注释类型、ProcessingInstruction、Comment类型
         * document对象有两个访问子节点的快捷方式: documentElement、childNode属性
        */
       
        // documentElement
        const HTML = document.documentElement
        console.log(HTML)

        // body属性
        const BODY = document.body
        console.log(BODY)

        // doctype属性去的documentType节点
        let DOCTYPE = document.doctype
        console.log(DOCTYPE)  // <!DOCTYPE html>
    </script>
</body>
</html>